A friend of mine has just purchased a 1905 Mannlicher that has been re-chambered for 8 x 57 Mauser. It was originally 8x56MS. The rifle is in great shape, but will this action handle the 8x57 Mauser cartridge?. Any info would be greatly appreciated.

This vintage of MS action should be limited to ammo loaded to pressures similar to the original 8X56MS chambering. If you chamber it for the 8X57 case, use U.S. factory pressure-level ammo, and you should be OK. Avoid the 50K level loads! Also, check the action to make sure the magazine will accept and feed the *X57 brass before you barrel it. It should, but the magazines were caliber-specific!

DPM---

I hope he got it REALLY cheap. The magazine is made for the 8x56MS.

The base diameter of the 8x57 is about .010 larger than the 8x56 and the shoulders are in different places.........that means they don't fit.

You need a new barrel......and an 8x56MS reamer.

DPM

There are a good number of M-S' that have been rechambered to 8x57 from 8x56. However, it was the 1908, not the 1905 that was 8x56.
First, check the underside of the barrel and receiver to see what bore it was originally. Make sure you don't see a "9" anywhere.
Then try to load 5 rounds of 8x57 into the magazine. If you can only load 2 or 3, then the rotor was not modified from the 56mm cartridge. If you can load and eject all 5 without incident, then the conversion was done properly.
The M-S action is strong and can handle factory 8x57 in its origianl form. No high pressure reloads, though.